Acoustical barrier fence



July 9, 1963 H. c. HARDY 3,096,847

ACOUSTICAL BARRIER FENCE Filed Dec. 7. 1960 INVENTOR. liaward Cffamfy United Stats atet 3,996,847 Patented July 9, 1 963 3,096,847 ACOUSTICAL BARRIER FENCE Howard C. Hardy, Northlake, 111., assignor to Stanray Corporation, Chicago, Ill., a corporation of Delaware Filed Dec. 7, 1960, Ser. No. 74,402 4 Claims. (Cl. 181-33) This invention relates to the enclosure of sound sources by acoustical barriers intended to be used primarily outdoors to prevent the radiation of noise to nearby neighborhoods and to personnel in the immediate vicinity, the principle being to make arrangements to deflect the sound in an upward direction. In particular, this scheme is applicable to the reduction of noise of aircraft engines on commercial and military aircraft when they are on the ground during runup. It could also be used for the sound isolation of the noise from any reaction motor.

It has been found by model studies that structures of the kind described will reduce the noise between and 30 decibels depending on the geometry and the need of the particular site.

The principle of this invention is that the barrier walls are inclined from the horizontal anywhere between 45 and 80 degrees. By inclining the walls in this manner, the sound reverberation, which is characteristic of vertical walls, is eliminated and the sound is directed upwards. The walls are also arnanged .a design to conform to the geometry of the object being enclosed. This, in some cases, would be an airplane, and the barrier walls would conform to the wing and fuselage structures. In the case of airplanes, the front of the structure would be a removable gate which would allow the airplane or other source to be towed into the structure.

Another object of the invention is to make use of the surfaces of the aircraft itself, the fuselage, wings, and rear stabilizers, in conjunction or combination with the enclosure Walls to baflle and beam the sound away from the directions which would disturb the surrounding area.

Other objects and advantages of the invention will appear in the tollowing description thereof.

Referring now to the accompanying drawing forming part of application and wherein like reference charac. ters indicate like parts;

FIGURE 1 is a top plan view of an enclosure tor an airplane for dispersing the noise therefrom.

FIGURE 2 is a front elevation of FIGURE 1.

FIGURE 3 is an enlarged transverse section through the enclosure wall or fence on line 3-3 of FIG. 1.

The invention contemplates the use of specially designed bafile walls arranged in a fashion about an airplane so as to direct the sound from the plane engines upward and to pnovide acoustical shield in all directions. Oohsidering the structure of FIGURE 1, the principal wall element is an A-frame as shown in FIGURE 3 at 10. The legs 12 and 14 of said A-f-rame converge upwardly toward each other and are connected at their tops by a bar 16. This A-fmalnc supports impervious wall sections .18 which are secured thereto in any acceptable manner. These wall sections 18 may or may not extend to ground level, entirely covering the supports, or leaving a narrow opening :at the base of each section, as indicated at 20, and a space between the upper edges of the wall sections (18 as shown at 22. These wall sections are the height requined to provide the optimum shielding tor the particular plane witln'n the enclosure. For the current series of jet aircraft, it has been found that a barrier fence of 20 feet or so in height is suflicient.

The wall sections on the A-frame supports are positioned angularly with respect to the ground from about 4580 and are shown on the drawing as at about 75. The inclination of the wall sections 18 to the horizontal is minimized in FIGS. 1 and 2, but the showing in these 2 figures and v at in FIGURE 3 is believed to be well within the limits stated. In cases where it may only be necessary to shield the sound in but one direction from the plane, it is readily conceivable that but approximately one-half of an enclosure is all that would be necessary.

The fence structure is secured to the ground apron 23 in any desired manner so that the blast, or heavy windstorms, would not dislodge the structure from its proper location.

Also it should be noted, the fence provides considerable protection of the area within the enclosure firom strong or high winds.

The wall sections are arranged in a sort of six sided figure which conforms quite closely to the overall configuration of the airplane indicated at 2'5, and appropriate to the noise control of airplanes which have engine pants mounted on swept back wings 42. Such airplanes are the DC 8, Boeing 707, Boeing 720, the Convair 880 and others. Such an arrangement consists of the two opposite parallel side walls 24-24; two walls 26-26 issuing from the rear edge of walls 24-24 at an angle of about 45 thereto and converging toward the rear of the aircraft; and two parallel walls 28-30 issuing from the rear edge of walls 26-26, which walls 28-30 are also parallel to walls 24-24. A rear deflecting barrier 32 joins the rear edge of walls 28 and 30. At the forward end of each such enclosure is a pair of gate members 33-33, hinged as at 34-34 along one vertical edge thereof to the side walls 24-24. While I have shown these gate sections as being hinged, it is obvious they could be operated by side Wise displacement, vertical rise, angular displacement, or any combination of these, the operation of which would substantially close the gates about an airplane housed within the enclosure. These gates are not as high necessarily as the other walls, and are moved out of the way to allow backing in of the plane. In most cases the plane would be towed into the enclosure and the gates closed before operation.

In FIGURE 1, the plan shows three of such enclosures, the two outer enclosures being identical and spaced from each other, and an intermediate enclosure, facing in the reverse direction. By the arrangement shown the two intermediate walls 24-24 and 26-26 are common to the enclosures on [opposite sides thereof. This arrangernent of enclosures could be continued to provide for any number of planes at a time that may be desired, and the enclosures would open alternately in opposite directions.

Another element, but not an absolutely necessary one, in the overall treatment is the location of table-like structures 40-40 just to the rear of the airplane wings 42, and supported on posts 44 at :about the height of the wings. The major portion of v e engine blast and accompanying sound would therefore be confined below the tables. The tables 40 are of truncated triangular shape, the bases of the triangles being adjacent :and panallel to the walls 26-26 of the respective enclosures, and the apexes cut off in substantial conformity with the outline of the rear portion of the fuselage, \as clearly seen in FIGURE 1.

From the above it is seen that l have devised a sound barrier for dispensing the noise of aincraft and preventing it from disturbing neighborhood areas.

When a jet airplane is placed within one of the enclosures and the motor started, the sound therefrom is partially directed downward by the wing surfaces and this enhances the protective nature of the walls. The sound to the rear of the plane is further shielded by the table like structures 40 when used and which aid the wings in directing the sounnd closer to the wall Where it has more shielding. It should be noted too that the enclosure provides no hindrance to the intake of air by the jet.

It has been discovered experimentally by model test-s 3 that arrangements of the kind disclosed give more sound reduction than could be predicted by text book theory. This reduction is believed attributable partly to deficiencies in the theory and partly to the geometric considerations whereby the plane itself in cooperation with the walls acts as a part of the total barrier.

It should be noted too that the device also effectively controls the blast from an aircrafit engine so as to direct it upwardly and over the top of the barrier fence away from nearby personnel or enplaning passengers.

. I claim:

1. A sound barrier and blast deflector fence for suppressing sound energy from an airplane engine and defleeting the blast therefrom upwardly and over said barrier fence, said fence comprising inclined upright walls having impervious surfaces arranged in hexagonal shape so as to closely follow the outline of an airplane to ditfraot the sound and deflect the blast from said airplane upwardly, the inclination of the fence and arrangement of same in close proximity to the airplane causing the surface of the airplane to conjointly act with the fence in attenuating the sound.

2. A sound barrier for suppressing sound energy containing a substantial level of sound at frequencies Within the audible range emitted from an airplane, said barrier comprising fixed inclined upright walls arranged to closely follow the configuration of said airplane, gates movably attached to opposite side wall-s of said barrier for closing the walls about the airplane, and table like structures immediately to the rear of the Wings of said airplane and extending to the walls at a level above the airplane engines whereby the sound of said airplane engines is effectively reduced by being reflected from the barrier walls and said airplane.

3. A barrier for deflecting the blast and sound issuing from the nozzle of a reaction motor, said barrier comprising inclined walls arranged to closely conform to the con figuration of said reaction motor and associated structure or airframe, said barrier having the cross section of an A-frame, impervious surfaces attached to the legs of said A-fr-ame and covering both sides of said A-frame from the top thereof to within a short space from the ground.

4. A sound barrier for suppressing sound energy containing a substantial level of sound at frequencies within the audible range emitted from an airplane engine, said barrier comprising a fence having an impervious surface inclining upwardly and away from said airplane, said fence being arranged so as to closely conform to the configuration of the airplane, and table like structures positioned to the rear of the wings of the airplane and at a level immediately above the exhaust of said engine, to confine the sound thereunder and direct it to said barrier fence.

References Cited in the file of this patent UNITED STATES PATENTS 1,780,102 Watt Oct. 28, 1930 1,925,139 Fellers Sept. 5, 1933 2,059,898 Osborne Nov. 3, 1936 2,974,910 Lynn Mar. 14, 1961 FOREIGN PATENTS 543,705 Canada July 16, 1957 815,271 France Apr. 5, 1937 774,550 Great Britain May 8, 1957 1,186,310 France Feb. 23, 1959 OTHER REFERENCES Noise Control, vol. 5, No. 4, issue of July 1959, pages 12-14 and 54. 

1. A SOUND BARRIER AND BLAST DEFLECTOR FENCE FOR SUPPRESSING SOUND ENERGY FROM AN AIRPLANE ENGINE AND DEFLECTING THE BLAST THEREFROM UPWARDLY AND OVER SAID BARRIER FENCE, SAID FENCE COMPRISING INCLINED UPRIGHT WALLS HAVING IMPERVIOUS SURFACES ARRANGED IN HEXAGONAL SHAPE SO AS TO CLOSELY FOLLOW THE OUTLINE OF AN AIRPLANE TO DIFFRACT THE SOUND AND DEFLECT THE BLAST FROM SAID AIRPLANE UPWARDLY, THE INCLINATION OF THE FENCE AND ARRANGEMENT OF SAME IN CLOSE PROMIMITY TO THE AIRPLANE CAUSING THE SURFACE OF THE AIRPLANE TO CONJOINTLY ACT WITH THE FENCE IN ATTENUATING THE SOUND. 